1. Field of the Invention
The present invention relates to a lighting apparatus using microwave, and more particularly, to a resonator of a microwave lighting apparatus having a mesh structure which is capable of preventing microwave transmitted through a waveguide from leaking and transmitting light radiated from a light bulb outwardly, and its manufacturing method.
2. Description of the Background Art
A microwave lighting apparatus is an instrument to apply microwave to an electrodeless light bulb to obtain a visible ray or ultraviolet rays therefrom. The a lamp adopting microwave lighting apparatus has a long lifespan and an excellent illumination effect compared to the general electric lamp or a fluorescent lamp.
FIG. 1 is a vertical-sectional view of a general microwave lighting apparatus.
As shown in FIG. 1, the microwave lighting apparatus includes a magnetron 5 for generating microwave, a waveguide 3 for transmitting the microwave from the magnetron 1, a light bulb 5 for generating light as a substance encapsulated in the light bulb is turned to plasma by the microwave energy transmitted thorugh the waveguide 3, and a resonator 20 for covering the front side of the waveguide 3 and the light bulb 5 to prevent microwave from leaking and transmitting light radiated from the light bulb 5.
With this fundamental structure, the microwave lighting apparatus further includes a high voltage generator 7 for boosting a common AC power to a high pressure and providing it to the magnetron 1, a cooling unit 9 for cooling the magnetron 1 and the high voltage generator 7, a reflection mirror 11 for collectively reflecting the light generated from the light bulb 5 forwardly, a light bulb motor 13 and a motor shaft 15 for rotating the light bulb 5, and cooling the heat while discharging the light, and a controller (not shown) for controlling varous factors including the high voltage generator 7 and the cooling unit 9.
In the microwave lighting apparatus, when the controller inputs a drive signal to the high voltage generator 7, the high voltage generator 7 boosts a received AC power and provides the boosted high pressure to the magnetron 1.
The magnetron 1 generates microwave having a very high frequency as being oscillated by the high pressure supplied from the high voltage generator 7, and thusly generated microwave is radiated into the resonator 20 through the waveguide 3 to discharge the substance encapsulated in the light bulb 5 and generate light having an inherent discharging spectrum.
In this manner, the light generated from the light bulb 5 is reflected to the front side through the mirror 12 and the reflection mirror 11 and lights a place of its insulation site.
FIG. 2 is a perspective view of the resonator used for the microwave lighting apparatus in accordance with a conventional art, and FIGS. 3A and 3B are a detailed view of the portion xe2x80x98Axe2x80x99 of FIG. 2 and sectional view taken along line Bxe2x80x94B of FIG. 2, respectively.
With reference to FIG. 1, the resonator 20 has a metal mesh form and is assembled at the side of exit 3a of the waveguide 3, so that it impounds microwave transmitted through the waveguide 3 and transforms the microwave energy to light within the light bulb 5, and at the same time, prevents the microwave from leaking and transmits the light generated from the light bulb 5 outwardly.
With reference to FIGS. 2 and 3, the resonator 20 includes, besides a portion of the opened portion 20a, a cylindrical unit 21 on which a plurality of holes 20b are formed by an etching process and a lid unit 25 formed convex and connected to the front portion of the cylindrical unit 21, having a plurality of holes 20b. 
The cylindrical unit 21 includes a mesh portion 22 for preventing microwave from leaking and transmitting light, and a fixed portion 23 fixed at the outlet portion of the waveguide 3. The fixed portion 23 is not subjected to the etching process. The fixed portion 23 included a plurality of slit portions 23a, so as is to be extended and easily assembled when it is installed at the waveguide 3.
FIG. 4 is a flow chart of a process of manufacturing the resonator in accordance with the conventional art.
The process for manufacturing the resonator will now be explained with reference to FIGS. 2 and 4.
First, in order to fabricate the cylindrical unit 21, a metal thin film of a predetermined thickness made of a stainless steel or phosphor bronze is cut in a rectangular shape, and the remaining portion except the fixed portion 23 is etched to form holes 20b to form a mesh portion 22.
The holes 20b formed by etching the metal thin film has such a size as to prevent leakage of microwave and a maximum aperture efficiency so that the light radiated from the light bulb 5 of FIG. 1 can be emitted outwardly at the maximum.
Next, the mesh thin film is bent to a cylindrical shape and the both end portions are put into contact and welded. At this time, the both end portions are put into contact and directly welded, or as shown in FIG. 3A, a reinforcing member 24 is applied on the portion where the both end portions 21a and 21b are put into contact and welded to fabricate the cylindrical unit 21.
At this time, it is to be cautioned that the both end portions 21a and 21b of the mesh thin film shouldn""t be welded as being folded. The reason for this is that, if a step is formed at the welded portion, when the resonator 20 is assembled to the waveguide 3, a gap occurs between the resonator 20 and the waveguide 3, through which microwave may be leaked.
In order to fabricate the lid unit 25, a metal thin film with a predetermined thickness made of stainless steel or phosphor bronze is cut in a circle form and etched to form the holes 20b to form the mesh structure like the cylindrical unit 21.
Thereafter, a lid unit 25 is fabricated with its circumferential marginal portion bent so as to couple the mesh thin film to the cylindrical unit 21.
Next, the cylindrical unit 21 and the lid unit 25 are coupled and the coupled portion is welded to fabricate the resonator 20, and then silver or platinum or a platinum family is plated on the surface of the resonator 20 to heighten the reflectivity of light and reduce an electric resistance of the surface, thereby completing the resonator 20.
However, the conventional resonator has the following problems.
That is, for example, first, since the rectangular thin film and the circular thin film are etched to form the holes 20b and welded, the fabrication process of the resonator 20 is complicated.
Secondly, if the welded portion is detached due to intense heat generated in the process that the microwave energy is switched to the light energy, the microwave may leaked outwardly.
Thirdly, when the resonator is fabricated by using the welding method, even though the welded portion is not detached, it may be oxidized to be detached due to the intense heat generated from the light bulb 5 of the resonator 20, a long-time reliability is not guaranteed.
Fourthly, in the case that the cylindrical unit 21 of the resonator 20 is formed, since the holes 20b are not formed at the welded portion and the welded portion by coupling the cylindrical unit 21 and the lid unit 25 as shown in FIG. 3B, the light radiated from the light bulb 5 is not transmitted therethrough, causing a problem that the aperture efficiency of the whole resonator 20 is degraded and the light efficiency of the lighting apparatus is accordingly degraded.
Therefore, an object of the present invention is to provide a resonator of a microwave lighting apparatus that is capable of preventing microwave from leaking, heightening the whole aperture efficiency and improving a light efficiency by integrally forming a portion with a mesh structure without a joint by not welding it.
Another object of the present invention is to provide a method for manufacturing a resonator of a microwave lighting apparatus that is capable of facilitating manufacturing of a resonator and manufacturing a resonator in various forms as necessary by integrally manufacturing the resonator without a joint by using an electro-forming method.
To achieve these and other advantages and in accordance with the purpose of the present invention, as embodied and broadly described herein, there is provided a resonator using microwave lighting apparatus including a mesh portion formed in a cylindrical shape with one side opened, at least one portion of which prevents microwave transmitted through a waveguide from leaking and light radiated from a light bulb is transmitted outwardly, the mesh portion being formed integral without a joint.
To achieve the above objects, there is also provided a resonator of a microwave lighting apparatus including an opening portion formed connected to a waveguide at one side of a cylindrical portion and a clogged front portion at the opposite side of the opening portion, a mesh portion is formed at the cylindrical portion and the front portion and connected through a fixing unit, each mesh portion is integrally formed without a joint.
To achieve the above objects, there is also provided a method for manufacturing a resonator of a microwave lighting apparatus including the steps of: forming a cylindrical resonator with one side opened and the other side clogged by using an electro-forming method to have a mesh structure without a joint; and heat-treating the resonator to reinforce its strength.
To achieve the above objects, there is also provided a method for manufacturing a resonator of a microwave lighting apparatus including the steps of: forming a cylindrical body with both sides opened by using an electro-forming method to have a mesh structure without a joint, separately fabricating a front portion in a mesh structure, attaching it to one side of the cylindrical body to form a resonator; and heat-treating the resonator to reinforce its strength.
The foregoing and other objects, features, aspects and advantages of the present invention will become more apparent from the following detailed description of the present invention when taken in conjunction with the accompanying drawings.